Peracid epoxidation of fatty acid esters



United States Patent i PERACID EPOXIDATION OF FATTY ACID ESTERS Frank P.Greenspan, Buffalo, N. Y., assignon'by'mesne assignments, to FoodMachinery and Chemical Corporation, San Jose, Calif., a corporation ofDelaware No Drawing. Application March 23, 1954, Serial No. 418,208

Claims. or. 260-3485) This application pertains to a novel type ofepoxidized triglycerides and more particularly to a method of partiallyepoxidizing triglycerides such as occur in unsaturated oils.

Methods for epoxidizing unsaturated oils by means of an organic peracidhave been described previously. In these methods the ethylenicunsaturated material is treated with a quantity of organic peracidsuflicient to epoxidize substantially all double bonds present in thematerial. In other words, previously published epoxidation methods,starting out with an oil possessing a certain degree of ethylenicunsaturation, were performed in such a way as to result in a fullyepoxidized oil possessing essentially no ethylenic unsaturation. Suchfully epoxidized oils were found to be suitable as plasticizers forpolymeric substances, such as polyvinyl chloride, either as such or inform of their derivatives.

Because unepoxidized oils, possessing original unsaturation, are notcompatible with plastics which it is desired to plasticize, previousepoxidation methods all aimed at complete epoxidation so as to leaveonly a marginal amount of unsaturation. I have now found that undercertain conditions, oils which have not been fully epoxidized are notonly compatible with plastics but actually have better performancecharacteristics than fully epoxidized oils. However, such partiallyepoxidized oils cannot be produced by arbitrarily restricting the extentof epoxidation, but have to be produced by a strictly controlledepoxidation process. Such partially epoxidized oils furthermore requirein their manufacture, reduced amounts of epoxidizing agent, such asperacid or hydrogen peroxide, because obviously partial epoxidation of agiven quantity of a given oil requires less reactants than completeepoxidation. Thus partially epoxidized oils prepared in accordance withthis invention have been found to be not only better in performance butalso cheaper to manufacture than fully epoxidized oils. Moreover, thesenovel partially epoxidized oils have various useful properties ofinterest in the manufacture of intermediate detergents, lubricantadditives, etc.

I have now found that such partially epoxidized oils can be produced bya critically modified epoxidation process. In epoxidation methodsdesigned. to produce fully epoxidized oils, the amount of peracid usedis calculated on the amount of ethylenic unsaturation present in thetoil. That is to say, that ordinarily at least 1 mole of peracid orhydrogen peroxide is employed for each double bond in each mole of theunsaturated fatty acid chains in the oil. Thus suflicient peracid isavailable to transform substantially all double bonds present into thecorresponding epoxy groups. Such epoxidation reactions may be carriedout with prepared organic peracids such as peracetic acid, performicacid, perbutyric acid and others. These reactions may also be carriedout using the so-called in situ method, wherein peracid in formed duringthe course ofthe reaction in the reaction medium from calculatedquantities of hydrogen peroxide and the corresponding organic acid.Furthermore, such epoxida- Patented Oct. 22, 1957 tion reactions, usingprepared peracids or peracids formed in situ, may be carried out with orwithout a solvent present in the reaction mixture, which solvents may bebenzene, hexane or other inert solvents.

In contrast to epoxidation methods resulting in complete epoxidation,the present invention pertains to a method resulting in a controlled anddefined partial epoxidation. Here epoxidation is carried out in such amanner that substantially all of the ethylenic unsaturation in thosechains of the oil that are mono-unsaturated fatty acid chains isepoxidized but only one double bond epoxidized in those chains that arepoly-unsaturated fatty acid chains. There results a defined epoxycompound con taining saturated fatty acid chains, saturated epoxy fattyacid chains and unsaturated epoxy fatty acid chains. This controlledepoxidation method and the resulting products are, therefore, distinctand different from methods which arbitrarily restrict degree epoxidationand produce a random distribution of epoxy groups and double bonds.Taking into account total unsaturation; that is total number of doublebonds in a naturally occurring oil and taking into account theapproximate per cent fatty acid composition of such oils, it becomesposible to calculate the amount of peracid required to produce a defineddegree of partial epoxidation.

The amount of peracid required for such partial epoxidation will, ofcourse, vary with the unsaturated oil to be treated because thecomposition of such oils; that is, their content of mono-ethylenicunsaturated higher fatty acid, di-ethylenic unstaurated higher fattyacid and poly-ethylenic unsaturated higher fatty acid varies. Corn oil,for instance, contains essentially only mono-and di-unsaturated acidsaside from some saturated acids. Linseed oil, on the other hand,contains mono-, di-, and triethylenic unsaturated fatty acids, togetherwith some saturated acids. As pointed out above, this composition of theoil, as well as the respective percentages of mono-, di-, andpoly-ethylenic unsaturated acids have to be taken into account whencalculating the amount of peracid required for defined partialepoxidation.

In any case of partial epoxidation of a naturally occurring oil, thereaction has to be carried out in such a manner that substantially alldouble bonds in the mono-unsaturated fatty acids present are epoxidizedand, therefore, disappear. However, the multiple double bonds in thedouble unsaturated and polyunsaturated fatty acids present,substantially one double bond only in each fatty acid chain should beepoxidized. Therefore, the proper amount of peracid is calculated inevery case so as to epoxidize all of the mono-unsaturated radicals andone double bond of the poly-unsaturates. Knowing the composition of agiven natural oil, calculation of the proper amount of peracid,sulficient to give the desired percentage of reacted double bonds, ispossible. Per cent double bonds reacted can also be expressed andchecked by calculating the iodine number to be expected for a certaindegree of partial epoxidation.

The proper amount of peracid required for partial epoxidation inaccordance with this invention is calculated on a molar basis andcorresponds to 1-1.3 mole of peracid for each double bond in each moleof monounsaturated esterified acid and 1-1.3 mole of peroxide for onedouble bond in each mole of polyunsaturated esterified acid.

An example for calculating the required amount of peracid may be givenfor the case of partial epoxidation of linseed oil. A typical commerciallinseed oil will contain about 19% oleic acid containing 1 double bondin the chain, 24% linoleic acid containing 2 double bonds in the chainand 47% linolenic acid containing 3 double bonds in the chain. Theequivalent of the total number of double bonds in a single average fattyacid' chain of the triglyceride can then be arrived at as follows:

19.0% oleic acid with 1 double bondequivalent to-0.'1901 24.1% linoleicacid with '2 double 7 bonds equivalent;to-0.482 47.4% linolenic acidwith 3 double V a 7 bonds equivalent to 1.422 Total number of doublebonds equivalent to 2.094

In the controlled :partial' epoxidation of linseed oil all of the doublebonds of the oleic acid chains, ne of the 2 double bonds'in the linoleicacid chains and one-of the 3 double bonds in the linolenic .acidchainsare. to be epoxidized. Therefore, the equivalent to .the number ofdouble bonds to'be reacted can be represented astollows:

19.0% oleic acid with 1 double bond equivalent to 0.190

24.1% linoleic acid with 1 double bond equivalent-$0.241 47.4%'linolenic acid with 1 double bond -equivalent1to 0.474 a Total numberof double bonds to be reacted equivalent to 0.905

The percent double bondsto betheoretically"reacted-in linseed oil isthen On this basis the theoretical amount of epoxidation rea gentrequired can be calculated. 1000 gram linseed oil with an iodine numberof 171 corresponds to- 6.74 mole of ethylenic unsaturation and toepoxidize 43.37 th'ere-' of requires 43.3% of 6.74 mole or 2.91 mole ofreagent.

The'percent'double bonds to be reacted can be cal-' culated in the sameway for other oils, whereby the fol"- lowing percent figures areobtained:

Percent Corn oil 68.0 Menhaden oil 33.2

Safllower oil v 55.0

Soybean oil 57.7

t This sample calculation will sufiice to indicate how the proper amountof peracid is to be calculated for different natural oils and fordifferent peracids. The following examples, although not restrictive,are intended to show partial epoxidation procedures for differentnaturally occurring unsaturated oils, different 'peracids as epoxidizingagents and different epoxidation techniques. Sample techniques aredescribed for the use of prepared peracids, for use of in situtechniques and,'furthermore, with and without the useof a solvent. Itshould be pointed out that in allcases, substantially quantitativeyields of the desired partially epoxidized oil were obtained inrelatively' very short reaction times and in a highly economical way.The various oils were subjected to controlled partial epoxidation; thatis, epoxidation was carried up to In the following Table 1, percentepoxidation reaction is given.

av percentage lower than. 100% epoxidation.

for'the different oils inthe different examples. The term,

percent epoxidation reaction" indicates how far the controlled partialepoxidation' has been carried. Variations.

in the figures given for percent epoxidation are essentially due to thefact that specific oil sampleswill frequently show a compositiondifferent from the average cOmposi: tion published for such oils.Moreover, as in organic reactions generally, a. certain excess of'epoxidizing rea gent is used in carrying out the reaction to take careof unavoidable losses and experimental errors. In general, the amount ofepoxidizing agent on a mole basis i s 1 to 1.3 moles per mole of desireddouble bond to be'reacted upon.

Before giving the actual experimental data and figures, the generalprocedure will be described here. All the following experimentalexarnples were carried out by Weighing the proper amount of the-oil tobe treated into a three-neck flask equipped'with a condenser,thermometer and stirrer. To. the oil was then added the proper amount ofsolvent, if a solvent was used. Where prepared peracids were employed, aquantity of a buffer, such as anhydrous sodium acetate, was then addedin an amount sufiicient to neutralize the mineral acid catalyst used inpreparing the. peracid and. present in the product as used. Thisaddition wasca'rried. but slowly over a period of time while maintainingtemperature between'approxi-' mately 15 and 35 C. For in situ operation,no anhydrous sodium acet'ate need be used and the calculated amount of"hydrogen peroxide-and concentrated organic acid. is added. In all'theexperiments, the temperature was kept near theupper. limit ofthe'temperature range after. all reagents have been added to thereaction flaskJ In each experiment the composition of the oilis given intermsof the constituent fatty acid.

After termination of the reaction, the product was washed with warmwater to remove residual free acid, and

acid: removal, where necessary, promoted by filtering through-anhydroussodium carbonate. Finally, the product was. dried with anhydrousmagnesium sulfate and.

filtered.

* Example 1' SAFFIJOWER =0IL Oil composition:

'Oleic acid percent 16.4

'Linoleic' acid do 77.7" 'Linolenic'acid do 0.3 Saturated acids do 6.6-

Iodine number 7.00 g. of safiiower oil, equivalent to 3.85 moles ofethylenic unsaturation, were reacted .in presence of 23 1g.'of.anhydrous sodium acetate with 2.41 mole peracetic acid (459.0 g.peracetic acid 40%). This was added 7 over a period ofl hour and 50minutes at 15 to 20 C.

and temperature then maintained at 20 to'30 C. for-a total reaction timeof 3 /2 hours. product was analyzed-and found to contain:

Percent epoxy Iodine number 1 700g. of safilower oil, equivalent"to3185' moles'of ethylenic unsaturation of the 's'amecompositionas used}in Example 1, were reacted in presence'of 23.1 g. of an hydrous sodiumacetate and'of 700 g. of benzenewitn 2.41 mole peracetic acid' (459.0 g.peracetic acid 40%)., This was added over a period of 1' hour and 50minutes at 15.10.20.- C. and temperature then maintained at20 to 30C.for atotalreaction time of 3 /2 hours. After wash-' ing, the product wasanalyzed and found to contain:

Percent epoxy Iodine num er mumwcoiziurenm After washing, the

ExampIe Z i m Example 3 1000 g. of safilower oil, equivalent to 5.5 moleofv ethylenic unsaturation, of the same composition as used in Example1, and 200 g. of benzene were put into the.

reaction fiask. To this were added 1.67 mole acetic acid (100 g. glacialacetic) and 6.7 g. of 50% sulfuric acid. Then 3.47 mole H202 (236.0 g.of 50% H202) were added over a period of 1 /2 hours while maintainingthe temperature of the mixture between 40 and 54 C. The reaction wascontinued for a total reaction time of 13 hours maintaining thetemperature at 60 to 65 C. After washing, the product was analyzed andfound to contain:

Percent oxirane oxygen 4.1 Iodine number 67 Example 4 1000 g. ofsafilower oil, equivalent to 5.5 mole of ethylenic unsaturation, of thesame composition as in Example 1, 1.67 mole acetic acid (100.0 g.glacial acetic) and 14.8 g. of 50% sulfuric acid were put in thereaction flask. Then 3.97 mole H202 (270.0 g. of 50% H202) were addedover a period of 1 hour while keeping the temperature between 53 and 65C. Total reaction time was 9 hours at a temperature of 60 to 65 C. Afterwashing, the product was analyzed and found to contain:

Percent epoxy 4.3

Iodine number Example 5 500 g. of safilower oil, corresponding to 2.75mole of ethylenic unsaturation, of the same composition as used inExample 1, and 21.5 g. of anhydrous sodium acetate were placed in thereaction flask. Then 1.73 mole of perbutyric acid (430 g. of 42%perbutyric acid) were added over a period of 2 hours while maintainingthe temperature at to C. The reaction was continued for any additional 2hours at to C. to give a total reaction time of 4 hours. After washing,the product was analyzed and found to contain:

Percent epoxy 4 4 Iodine number 56 Example 6 CORN OIL O11 composition:

Oleic a id perc nt 46.3 Linoleic acid do 41.7 Saturated acids d0 12.0Iodine number 119 1500 g. of corn oil, equivalent to 7.03 moles ofethylenic unsaturation, were reacted in presence of 55.0 g. of anhydroussodium acetate with 5.27 mole of peracetic acid (1005.0 g. peraceticacid This was added over a period of 2 hours and minutes at 15 to 20 C.and the temperature was then permitted to rise slowly over a totalreaction time of 4 hours and 15 minutes to C. After washing, the productWas analyzed and found to contain:

Percent epoxy 5.3

Iodine number--- 24 Example 7 LINSEED OIL Oil composition:

Oleic acid percent 19.0 Linoleic acid do 24.1 Linolenic acid do 47.4Saturated acids do 9.5 Iodine number 171 1000 g. of linseed oil,equivalent to 6.74 moles of ethylenic unsaturation, were reacted inpresence of 32.0 of anhydrous sodium acetate with 3.34 mole peraceticacid (635.3 g. peracetic acid 40%). This was added over a period of 1hour and 10 minutes at a temperature of 17 to 20 C. and the temperaturethen maintained at 17 to 33 C. for a total reaction time of 3 hours and1 5 minutes.- After washing, the product was analyzed and 600 g. ofmanhaden oil, equivalent to 4.12 moles of ethylenic unsaturation, werereacted in presence of 14.3 g.

of anhydrous sodium acetate with 1.50 mole of peracetic acid (285.0 g.peracetic acid 40%). This was added over'a period of 1 hour and 5minutes at about 20 C.

and the temperature then maintained at 24 to 32 C. for. a total reactiontime of 3 hours and 45 minutes. After washing, the product was analyzedand found to contain::

Percent epoxy 3.7 Iodine number 100 Example9 SOYBEAN OIL Oilcomposition: i Palmitoleic acid percent 0.4 Oleic a id d 29.7- Linoleicacid do 50.4 Linolenic acid do 6.5 Saturated acids do 13.0: Iodinenumber"; 135;

.600g..of soybean oil, equivalent to 3.19 moles bf ethylenicunsaturation, were reacted in presence of 18.3

g. of anhydrous sodium acetate with 1.92 mole of per-J;

acetic acid (365.0 g. peracetic acid 40%). This was added over a periodof 1 hour and 10 minutes at 20 to 25 C. and temperature then maintainedat 26 to 33 C,

After washing, the product was analyzed and found to contain:

for a total reaction time of 3 hours and 20 minutes.

Percent epoxy Iodine number Example 10 SAFFLOWER OIL 100g. of saflloweroil, corresponding to 0.550 moleof ethylenic unsaturation, of the samecomposition as used in Example 1, and 0.165 mole of formic acid (8.46 g.

of formic acid) were placed in the reaction flask. Then 0.396 mole ofH202 (27.0 g. 50% H202) were added over a 5 minute period at 26 C. andthe tempera-f ture. then maintained between 26 and 35 C. foradditional22 /2 hours. After washing, the product was analyzed and found tocontain:

The over-all efiiciency of the method of this invention is furtherindicated by the very high and, in some cases, theoretical yield ofpartially epoxidized triglyceride obtained. These yields were: Example:

Percent epoxy Iodine number Yield percent 96 SwOOQO I-PWN .of 1 to 4hours.

' esterified acid.

:From the foregoing 3 description and examples;

be seen that there is outlined a" method for obtaining stated'partiallyepoxidized ethylenic unsaturated higher fatty "ciiIs'inperi'ods'oftimeshorter than; required for complete" epoxidation." 'By limitingthe amount of epoxidizing reagent to substantially that required toepoxidize the ethylenic unsaturatiorrin a mono-unsaturated chain,

' and to that required to epoxidize one. only of the ethylenic 7acid,,suc-h as per'acetic acid, or may :he hydrogen peroxide and thelower-aliphatic acid in the presence of from about 0.5%..Jto 51%sulfuric acid.. Where the peracid .is employed, the temperature ofreaction is preferably low, from about 15 C. to 35 C. and the reactiontime, on the order Where peroxide and lower aliphatic acid are employed,'the'temperature of reaction is somewhat higher and the duration of 'thereaction longer.

What is claimed is: J

'1. The method of ,epoxidizing unsaturated fatty acid esters containedin naturally occurring unsaturated oils which comprises. heating. saidoilsunder epoxidizing conditions-with: a lower aliphatic peracid, theamount of which correspondsto Lto 1.? moles of peracid foreach double.bond in each moleof mono unsaturated esterified acidplus .1 to l.3 molesofilowenaliphatic peracid for one. double. bond only of each mole ofpolymnsaturated '2. Themethod .of .epoxidizing. unsaturated fatty acidesters: contained in naturally occurring unsaturated oils whichcomprises heating said oils under epoxidizing conditions with hydrogenperoxide; a lower aliphatic acid and sulfuric acid, the amount of thehydrogen peroxide corresponding to 1 to 1.3 moles, and the amount oflower aliphatic acid corresponding to about 0.25. to l mole'for' eachdouble bond in each mole of mono-unsaturated esterified acid plus 1" to1.3-rnoles of hydrogen peroxide, and theamountof sulfuric acidcorresponding to about 0.5 to 5% of the total weight of lower aliphaticacid and hydrogen peroxide for one double bond only of each mole ofpoly-unsaturated esterified acid. 7

'3.:The method of epoxidizing unsaturated fattyacid esters contained innaturally, occurring unsaturated oils whichcomprises heating said oilsunder epoxidizing conditions with peracetic acid, the amount of whichcorresponds to 1 to 1.3 moles of peracid for each double bond in eachmole of mono-unsaturated esterified acid plus onlyof eachimole ofpoly-unsaturated esterifiedlacid.

1, to 1.3'moles of perac etic acid for one double bond 4. Themethod ofepoxidizingunsaturated fatty ditionswithperfor'mic acid, the amount ofwhieneone;

sponds to l to 1.3 molesofperacid for each-double bond in each mole ofmono-unsaturated esterified 'acidplus 1' to 1.3 moles ofperfortnic acidfor one double bond'o'nly of each mole of'pol'y-unsaturated esterifiedacid.

5. The method of epoxidizing unsaturated fatty acid esters contained innaturally occurring unsaturated oils whichcomprises Qheating said oilsunder epoxidizing con= ditions with perbntyrie acid, the amount of whichcorre-' sponds to 1 to'1.3 moles of peracid for each double bond in eachmole of mono-unsaturated esterified acid plus' 1 to l.3.molesofperbutyric acid for one doublebond only of each moleoftpoly-unsaturated esterified acid.

6. The method of epoxidizing safflower oil which com- 7 corresponds to.about 33.2% of that required completely to epoxidize the oil.

9; Th'e method of epoxidizing soybean oil which com-- prises heating'thesoybean oil under epoxidizing conditions with alower aliphatic per'acid,the amount of which corresponds to about 57.7% of that requiredcompletely to epoxidize the oil. V

10. The method of epoxidizing linseed oilwhich comprises heating thelinseed oil under epoxidizing conditions with a lower aliphatic pefacid,the amount of which corresponds to about 43.3% of that requiredcompletely to epoxidize the oil. 5

References Cited in the file of this patent UNITED STATES PATENTS2,312,535 Fieser "Mar. 2, 1943 2,485,160 Ni'ederhauser et a1 Oct. 18,1949 2,569,502 Swern a a1. Oct. 2, 1951 OTHER REFERENCES Findley et aL:J. Am. Chem. Soc. 672412 (19 Ralston: Fatty Acids and Their Deriv., p.414 (1948), John Wiley and Sons.

a esters contained in naturally occurring'unsatiir'a'ted oils whichcomprises heating said oils under epoxidi zing' coii V

1. THE METHOD OF EPOXIDIZING UNSATURATED FATTY ACID ESTER CONTAINED INNATURALLY OCCURING UNSATURATED OILS WHICH COMPRISES HEATING SAID OILSUNDER EPOXIDIZING CONDITIONS WITH A LOWER ALIPHATIC PERACID, THE AMOUNTOF WHICH CORRESPONDS TO 1 TO 1.3 MOLES OF PERACID FOR ACID DOUBLE BONDIN EACH MOLE OF MONO-UNSATURATED ESTERIFIED ACID PLUS 1 TO 1.3 MOLES OFLOWER ALIPHATIC PERACID FOR ONE DOUBLE HOND ONLY OF EACH MOLE OFPOLY-UNSATURATED ESTERIFIED ACID.